Iontophoresis is to administer a drug through the skin or the mucosa by applying voltage to the skin or the mucosa and electrically causing migration of an ionic drug. An iontophoresis device is so constituted as to carry out medical care by sticking electrodes for an anode and a cathode for iontophoresis to skin at a predetermined distance from each other and leading the electric current generated in an electric current generator to the electrodes.
Further, the iontophoresis device has a structure of combination of layers for storing a pharmaceutical agent and the electrodes and a previously planed predetermined quantity of a pharmaceutically effective component and a variety of additives besides the component based on necessity are sealed for the purpose to keep the internal concentration of the drug in blood for a predetermined time.
Regarding the basic structure of the iontophoresis device with the above described constitution, many have been proposed for the purpose of improvement of the capability, operability and the economical properties. As exemplary ones, the techniques disclosed in National Publication of International Patent Application Nos. 7-507464, 8-503875, 8-505303, 8-508915, 10-509334, Patent No. 2542792, Japanese Patent Publication No. 6-47014, Japanese Patent Laid-Open Nos. 8-229140, 8-196644, 9-201420and the like, are known. However, it is difficult to practically commercialize this kind of device. One of the reasons for that is because of the complicated electrode structure of the iontophoresis device and the high cost following the complication. Further, as the factors of the structure complication, the retaining form of the drug storage layer, the retaining member structure for the layer and the conducting form for transmitting the electric current to the drug storage layer, are exemplified.
For example, in National Publication of International Patent Application No. 7-507464, proposed is a method of impregnating the drug retaining layer by disposing a capsule or porch enclosing water or an electrolytic solution in the upper portion of the electrode structure and breaking the capsule or the porch at the using time. The technique is for a produced agent of a type to be dissolved in use for the purpose of using a drug unstable in water. However, owing to its complicated structure, mass production is supposed to be difficult and further no joining means between the electrodes and the electric current output portion is disclosed to make the technique insufficient in practical application. Further, in Japanese Patent Publication No. 6-47014, disclosed is an apparatus in which the complicated electric circuits are simplified by installing an anode, a cathode, an electric current output portion and a drug storage layer all in a backing processed by molding and making the backing material be a conductive plastic. However, in this technique, there is a risk of pharmaceutical agent leakage from the drug storage layer in terms of the structure and the storage stability is also a problem.
Further, both of the above described two examples of the techniques, cannot be said to be economical structure since both internally comprise electric current output portions. Hence, taking the economical property into consideration, proposed is an apparatus in which an electric current output portion to be used repeatedly and disposable portions (electrode portions and drug storage portions) are separated. In the case of this apparatus, what important is the method how to connect the electrode portions neighboring the drug storage portions and the electric current output portion for supplying electric current to the electrode portions. For example, Japanese Patent Laid-Open No. 8-229140 discloses an agent of the type to be dissolved at the using time. In this agent, lead portions of the electrode layers are led out a backing by forming holes in the backing so as to be connected with the electric current output portion. The electrode layers are the types incorporated in the molded backing and thus are not to be said to be suitable for mass production.
Further, those disclosed in the Japanese Patent Laid-Open No.8-196644 and Japanese Patent Laid-Open No. 9-201420 employ convexity terminals as connection means for the electrode layers and the electric current output portion. This form is widely employed as the constitution for electrodes for electrocardiogram and low frequency. However, from the manufacturing aspect, holes have to be formed in the backing to insert the convexity terminals, so that this form is not suitable for mass production and further since there is a risk of leakage of the components of the drug storage layer out of the terminal installation portion, there occurs a problem in storage. Further, from the viewpoint of use feeling, if convexity terminals with no flexibility are installed, the entire flexibility of the backing is deteriorated and simultaneously the property of attaching to the skin is also deteriorated. Further, it is reported that direct electric current flows from the terminal installation portion to irritate the skin and insulation covers for preventing direct electric current are required. Further, although using no such convexity terminals as described above, a structure body disclosed in Japanese Patent Laid-Open No. 10-234864 is provided with energizing hole portion in a recessed portion of a cup-like supporting body in order to connect an electrolytic layer disposed in the inside of the supporting body and an electrode layer formed in the outside and also, in this case, there is probability to cause a problem similar to those described above.
Further, National Publication of International Patent Application No.10-509334 discloses a connection method using no terminals for connection. The form is composed by providing the connection function in the electric current output portion side and sandwiching lead portion of a plane-type backing in which electrode are printed with the electric current output portion. This technique is advanced in the operational property, however the form of the drug storage layer is restricted in the point that the backing is plane-type one. For example, it is expected to be difficult to store a liquid or a gel with water-evaporating property in state as it is previously installed and in the case of the drug storage layer in such a form, it is forcibly required for the drug storage layer to be wrapped separately. Further, Japanese Patent Laid-Open No. 11-54855 discloses an electronic portion to be employed as an electrode of a low frequency therapeutic care apparatus by packing an electrolytic gel in a recessed portion in which an electric conductive pattern is printed. Further, National Publication of International Patent Application No. 10-509694 discloses a method for forming a patch for ion penetration curing in an inert atmosphere and wrapping it in order to prolong the storage period.
Regarding a conventional iontophoresis device, there are the following problems.
(1) The apparatus in which an anode, a cathode, an electric current output portion and a drug storage layer are incorporated in one packing has a complicated structure, so that mass production is made difficult and the cost is also high. Further, since the electric current output portion cannot be used repeatedly, the apparatus is not economical.(2) In the case of an apparatus in which an electric current output portion to be used repeatedly and disposable portions (electrode portions and drug storage portions) are separated, there is a problem to be solved in the connection means between the electrode portions in a backing and the electric current output portion. For example, in the case of using terminals in an apparatus in which a conductive gel is packed in a molded processed portion, leakage and evaporation of a drug-stored component are probable to take place. Further, depending on the connection means, the cost becomes high in some cases.(3) In some connection means of electrode portions and an electric current output portion, it is probable to deteriorate the flexibility of the entire body of the apparatus and to cause electric irritation in a human body.(4) In the case of plane-type backing in which electrodes are printed, the form of the drug storage layer is restricted and in the case where a drug storage layer with a high water content is formed, the molded backing has to have high sealing property, however heating is required at the time of the molding process, the electrode layers are significantly affected and it is probable for the electrode layers to be disconnected. Further, in the case of an electrode in which an electrolytic gel is simply packed in a recessed portion bearing a printed conductive pattern, leakage and evaporation of a drug-stored component are probable to take place and batch production in an inert atmosphere lead to cost up.